Blow mold device

ABSTRACT

The shifting of the parting line between split molds due to mold clamping force is prevented. A blow mold device ( 11 ) wherein a pair of split molds forming a blow cavity ( 12 ) are a set of molds, and a plurality of such sets are attached in parallel to mold-attaching plates ( 15, 16 ) with a clearance defined between adjacent sets. One split mold ( 13 ) is attached by bolts ( 17 ) inserted in bolt holes ( 23 ) in the form of loose holes in the mold-attaching plate ( 15 ) in such a manner as to allow relative lateral shifting of the split mold ( 13 ) and mold-attaching plate ( 15 ). The other split mold ( 14 ) is fixedly attached to the mold-attaching plate ( 16 ) by locating pins ( 18 ) and bolts ( 17 ). A joint is installed that integrally connects the two split molds to their parting surface and that is composed of a taper pin ( 19 ) and a socket ( 21 ) for preventing the shifting of the parting line.

FIELD OF THE INVENTION

The present invention concerns a blow mold device used in the case wherean injection-molded preform is blow-molded into a hollow mold such as abottle and a wide-mouthed container.

BACKGROUND ART

In an ordinary blow mold device, as shown in FIG. 6, split molds 1 a, 1b where a blow cavity 2 is formed in the parting face are served as aset of molds, a blow mold device 1 is composed of a plurality of setsthereof by arranging in parallel on mold-attaching plates 3, 3 by alocating pin 4 and a bolt 5 spacing with a clearance between the pluralsets, and the blow mold device is attached by making the mold-attachingplates 3, 3 into contact with the opposed faces of movable platens 6, 7inside and outside a mold clamping apparatus.

The inside movable platen 6 has a plunger 8 coupled to the back center,and an outside movable platen 7 has rods 9, 9 coupled to both sidespassing through the inside movable platen 6, so that both of theaforementioned movable platens 6, 7 move simultaneously facing to eachother, and the mold close of the blow mold 1 is executed in the middlebetween the platens, allowing the mold to open, close, and clamping byhydraulically operating the plunger 8 and rods 9, 9 simultaneously.

In such mold clamping apparatus, mold clamping force by the plunger 8acts on the central section of the inside movable platen 6 as pressingforce, while mold clamping force by the rods 9, 9 comes to acts on bothsides of the outside movable platen 7 as tensile force. Consequently,the distribution of opposed mold clamping forces is differently appliedon both platens, and both movable platens 6, 7 are deflected inwardly(chain line direction) and bent backward.

According to this deflection, the aforementioned mold-attaching plates3, 3 also finish up by deflecting similarly; however, as there is aspace between adjacent molds for split molds 1 a, 1 b, the split mold lawhere the mold-attaching plate 3 is attached on the outside movableplaten 6 finishes up by tilting inward, and on the contrary, the splitmold 1 b where the mold-attaching plate 3 is attached on the outsidemovable platen 7 finishes up by tilting outward. The shift due to thisinclination in the opposite directions increases gradually from thecentral section to both sides, and in the split molds 1 a, 1 b places atboth sides, as shown enlarged in the drawing, it becomes a considerableshifting of the parting line PL, and finishes up by creating alongitudinal shoulder on the side of the blow cavity 2.

If an injection molded preform (not shown) is pinched by the neck andinserted in the blow cavity 2 of such state, stretch blow molded full inthe cavity, the trace of the parting line is transferred on the middleof the side body section of a molded product therein, and left there asa considerably protruded stripe. The parting line mark on the body isundesirable for labeling or others processes, and is rejected asdefective for the packaging container of contents of high added value.

DISCLOSURE OF THE INVENTION

The present invention devised to solve the aforementioned problems ofthe prior art and has an object to provide a novel blow mold device thatcan prevent the shifting of the parting line between split molds eachother by the mold clamping force, by attaching one of a pair of splitmolds composing a set of molds in a state laterally movable in respectof the mold-attaching plates, and coupling both of them by a joint, andthereby solve the problem of the parting line mark on the product.

The present invention according to the aforementioned object is a blowmold devise attaching a plurality of sets of molds in parallel on andbetween a pair of mold-attaching plates with a clearance defined betweenadjacent sets of molds, each such one set of molds constituting a pairof split molds forming a blow cavity, wherein;

one split mold of the pair is attached with a bolt inserted in a loosebolt hole perforated in one mold-attaching plate so that the split moldand the mold-attaching plate can shift laterally and relatively in moldsclosing as far as within a space formed between the loose bolt hole andthe bolt inserted therein,

the other split mold of the pair is fixedly attached to the othermold-attaching plate with a locating pin implanted in the mold-attachingplate and a bolt, and in molds closing both split molds are connectedintegrally and closely on both parting faces of them, and both of ataper pin and a socket provided with the pair of molds as a jointoperate to secure both the molds mutually so as for a parting line notto fluctuating, and the pair of split molds as one set of molds forms aplurality of blow cavities, and the joint is buried between the blowcavities or on the parting faces of both sides.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and advantages of the present invention willbecome clear from the following description with reference to theaccompanying drawings, wherein:

FIG. 1 is a plane cross-section of a blow mold device according to thepresent invention;

FIG. 2 is a partial magnified view of the same;

FIG. 3 is a vertical view of the blow mold device as above;

FIG. 4 is a plane cross-section of the blow mold device as above duringthe deflection;

FIG. 5 is a partial magnified plane cross-section of another embodiment;

FIG. 6 is a plane view illustrating the deflection in a mold clampingapparatus where a conventional mold apparatus is attached; and

FIG. 7 is a plane cross-section of a conventional mold apparatus duringthe deflection.

BEST MODE FOR CARRYING OUT THE INVENTION

FIGS. 1 to 5 show embodiments of the blow mold device according to thepresent invention.

In the drawing, the numeral 11 indicates a blow mold, composed by takinga pair of split molds 13, 14 as a set of molds forming a plurality ofblow cavities 12, 12 on the parting face, and attaching three sets ofmolds in parallel to mold-attaching plates 15, 16 disposing a clearance.The split molds 13, 14 are attached on the mold-attaching plates 15, 16using bolts 17 and locating pins 18 similarly to the prior art, however,only the split mold 14 of one side is fixed by the locating pins 18,while the split mold 13 of the other side is fixed only by the bolts 17.

In the drawing, the split mold 14 is attached on the mold-attachingplate 16, by fitting a locating hole opened previously on the side faceof the mold to the locating pins 18 provided previously on the innerface of the mold-attaching plate 16, and fixing more securely with thebolts 17.

The split mold 13 is attached on the mold-attaching plate 15 byinserting the bolts 17 into bolt holes 23, in the form of loose holeshaving a diameter larger than that of the bolt 17, perforated on themold-attaching plate 15. In such a manner, the split mold 13 and themold-attaching plate 15 are allowed to shift relatively and laterally bya space between the bolt 17 and the bolt hole 23.

Moreover, a joint comprises a taper pin 19 and a socket 21 having afitting hole for preventing the shifting of the split mold 13 by thesplit mold 14, by coupling the split mold 13 and the split mold 14integrally by the mold closing. The joint is fixed by bolts 20, 22 andburied in upper and lower molds (refer to FIG. 4) between a pair of blowcavities 12, 12.

The position where the joint is buried is not limited between a pair ofblow cavities 12, 12, but it may also be buried, as shown in FIG. 5, inthe upper and lower molds outside the blow cavities 12, 12 by fixingwith bolts 20, 22, or it may also be laid by changing the taper pin 19on the split mold 13 side and the socket 21 on the split mold 14 side.

The blow mold 11 of the aforementioned composition is used by attachingthe split mold 13 side on an outside movable platen 7 of a mold clampingapparatus show in FIG. 6, and the split mold 14 side on an insidemovable platen 6.

In such a blow mold 11, the split mold 13 is attached on themold-attaching plate 15 so as to shift laterally only by the bolt 17,even when the mold clamping force by the plunger 8 acts on the centralsection of the inside movable platen 6 during the mold clamping, themold clamping force by the rods 9, 9 acts on both sides of the outsidemovable platen 7, and both movable platens 6, 7 are deflected with themold-attaching plates 15, 16, and bent inwardly from the position ofchain line in FIG. 3 and, moreover, as the split molds 13, 14 areintegrated laterally by the joint, the deflection of the mold-attachingplate 15 is absorbed by a space between the bolt 17 and the bolt hole23, and the both split molds 13, 13 are prevented from tilting inside bythe deflection of the mold-attaching plate 15.

Also, the split molds 14, 14 of both sides, which are fixed to themold-attaching plate 16 by the bolts 17 and the locating pins 18,finished up by tilting outward, due to the deflection of themold-attaching plate 16 which deflects with the inside movable platen 6.As the split mold 14 is integrated with the split mold 13 by a joint,and as the split mold 13 is attached on the mold-attaching plate 15 soas to shift laterally, the split mold 13 finishes up by tilting with thesplit mold 14 in the tolerance range of the space between the bolt 17and the bolt hole 23. Thereby, the shift of the parting line PL of theboth is prevented, solving the defective of the product due to theparting line mark.

After the relief of stress as mold clamping force, the deflection of thesplit molds 13, 14 becomes undone with inside and outside movableplatens 6, 7, removing the inclination of the split molds 13, 14, and asthe taper pin 19 of the joint faces directly to the engagement hole ofthe socket 21, they finish up by engaging each other when the moldsclose next time. In addition, the prevention of shift of the partingline PL improves the attaching accuracy of the parting finished splitmolds onto the mold clamping apparatus, decreasing the necessity ofrefinish.

Though not shown, the elimination of parting line mark on the product,the blow cavity for flat bottle that has been formed along the partingline PL can be formed at right angles the parting line PL, allowingthereby to increase the number of cavities, even for the blow mold offlat bottles where the number of cavities is low and limited compared tothe round body products.

INDUSTRIAL APPLICABILITY

While the presently preferred embodiment of the present invention hasbeen shown and described, it will be understood that the presentinvention is not limited thereto, and that various changes andmodifications may be made by those skilled in the art without departingfrom the scope of the invention as set forth in the appended claims.

1. A blow mold device attaching a plurality of sets of molds in parallelon and between a pair of mold-attaching plates with a clearance definedbetween adjacent sets of molds, each such one set of molds constitutinga pair of split molds forming a blow cavity, wherein; one split mold ofthe pair is attached with a bolt inserted in a loose bolt holeperforated in one mold-attaching plate so that the split mold and themold-attaching plate can shift laterally and relatively in molds closingas far as within a space formed between the loose bolt hole and the boltinserted therein, the other split mold of the pair is fixedly attachedto the other mold-attaching plate with a locating pin implanted in themold-attaching plate and a bolt, and in molds closing both split moldsare connected integrally and closely on both parting faces of them, andboth of a taper pin and a socket provided with the pair of molds as ajoint operate to secure both the molds mutually so as for a parting linenot to fluctuating.
 2. The blow mold device of claim 1, wherein: thepair of split molds as one set of molds forms a plurality of blowcavities, and the joint is buried between the blow cavities or on theparting faces of both sides.